This competing continuation application requests renewed support for the NRSA HIV Prevention Research Postdoctoral Fellowship Program at the Center for AIDS Intervention Research (CAIR), Medical College of Wisconsin. CAIR's postdoctoral fellowship program was established in 1996 and thus far has graduated 18 trainees (3 additional fellows currently are completing their second year of training). CAIR's postdoctoral fellows have been highly productive, and previous fellows are now making significant contributions to advance the field of HIV prevention research. During the renewal period, the 2-year training program will accept 3 new fellows every other year. The fellowship program curriculum includes seminars in HIV prevention research, ethics, and foundational areas of behavior change theory, research design, and data analysis; grant development and career development workshops; a manuscript writing workgroup; enrichment coursework at local educational institutions; required trainings in research ethics and human subjects protection; bimonthly journal club meetings; and active participation in multiple research studies. Each fellow is paired with a primary research mentor who provides guidance on all aspects of behavioral HIV prevention research, scholarly activities, and professional conduct. Additional, secondary mentorship relationships between faculty and fellows are actively encouraged. The HIV prevention research training program emphasizes hands on involvement in ongoing research projects at CAIR, as well as fellow-initiated research. During the first training year all fellows complete an independent research project, which is designed, implemented, analyzed, and written up for publication by the trainee, under the guidance of his or her primary research mentor, and with the support of CAIR's research support cores. Trainees have an opportunity to develop a small NIH grant during the second year of training. Fellows are integrated into ongoing studies directed by their mentors and/or other CAIR faculty. The wide variety of projects currently being undertaken at our multidisciplinary research center provides a wealth of opportunities for postdoctoral fellows to become actively involved in multiple research projects and to collaborate with program faculty on manuscripts and presentations. We believe that this combination of close mentorship by experienced HIV prevention researchers and multiple opportunities for hands on research experiences is essential to train fellows to become productive independent investigators.